Why you might struggle more doing cardio in the winter

10/11/2018

Doing cardio during the winter can feel tough for various reasons, the first being the short number of light hours in the day, which cruelly limits the time you have outdoors to run (where it is, admittedly, far more pleasant to exercise than on a treadmill). Then there’s the fact that it’s freezing outside, and that usually means you want to do very little else aside from cosy up indoors with a blanket and/or a glass of red wine. Not exactly conducive to exercise.

But it seems there’s also a scientific reason as to why some people might struggle more with cardio during the winter months. A new study published in the European Journal of Preventive Cardiology has revealed a link between higher vitamin D levels and increased cardiorespiratory fitness.

As we well know, the main source of vitamin D is sunlight. But in winter, our access to that is significantly less (in the UK, anyway), which may ultimately have an effect on our fitness when doing cardio exercise.

In order to reach their conclusions, the scientific researchers behind this study assessed the health data of 1,995 people between the ages of 20 and 49 years, making sure not to include those whose vitamin D levels were at the top and bottom 5 per cent extremes. The information was gathered from the US National Health and Nutrition Survey (2001–2004), and they noted participants’ oxygen consumption levels (as a marker of cardiorespiratory fitness) alongside vitamin D levels.

What the researchers found was that participants in the highest quartile of vitamin D levels had a significantly higher cardiorespiratory fitness than participants in the lowest quartile. The findings, the report states, are “robust”, but would now need to be validated with clinical trials to confirm the direct link.

“Our study shows that higher levels of vitamin D are associated with better exercise capacity,” said Dr Amr Marawan, one of the authors of the revelatory study, who went on to add that “the relationship between higher vitamin D levels and better exercise capacity holds in men and women, across the young and middle age groups, across ethnicities, regardless of body mass index or smoking status, and whether or not participants have hypertension or diabetes.”

If you don’t want your cardio performance to be knocked by a lack of sunlight, you’ve got a few options. Up your intake of vitamin D-rich foods, such as cheese, eggs, and fatty fish like tuna, mackerel, and salmon; invest in a vitamin D supplement; or – and this is my personal favourite – book a winter sun holiday somewhere exotic and hot.